de.codesourcery.eve.skills.util.SpringBeanInjector.java Source code

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Here is the source code for de.codesourcery.eve.skills.util.SpringBeanInjector.java

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/**
 * Copyright 2004-2009 Tobias Gierke <tobias.gierke@code-sourcery.de>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package de.codesourcery.eve.skills.util;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

import javax.annotation.Resource;

import org.apache.log4j.Logger;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;

/**
 * Parses a classes fields and methods for {@link Resource} annotations
 * and injects the corresponding spring beans.
 *
 * @author tobias.gierke@code-sourcery.de
 */
public class SpringBeanInjector implements BeanFactoryPostProcessor {

    private static final Logger log = Logger.getLogger(SpringBeanInjector.class);

    private static SpringBeanInjector INSTANCE;

    private BeanFactory factory;

    public SpringBeanInjector() {
        if (INSTANCE != null) {
            log.warn("SpringBeanInjector(): Creating singleton more than once ?");
        }
        INSTANCE = this;
    }

    /**
     * UNIT-TESTS ONLY.
     * 
     * @param instance
     */
    public static void setInstance(SpringBeanInjector instance) {
        INSTANCE = instance;
    }

    public static SpringBeanInjector getInstance() {
        return INSTANCE;
    }

    protected Object getBean(String name) {
        return factory.getBean(name);
    }

    public void injectDependencies(Object obj) {

        if (obj == null) {
            throw new IllegalArgumentException("Cannot inject into NULL object");
        }

        if (log.isTraceEnabled()) {
            log.trace("injectDependencies(): Injecting dependencies into " + obj.getClass().getName());
        }

        try {
            doInjectDependencies(obj);
        } catch (Exception e) {
            throw new RuntimeException("Failed to inject dependencies into " + obj.getClass().getName(), e);
        }
    }

    private void doInjectDependencies(Object obj)
            throws IllegalArgumentException, IllegalAccessException, InvocationTargetException {

        Class<?> currentClasz = obj.getClass();
        do {
            // inject fields
            for (Field f : currentClasz.getDeclaredFields()) {

                final int m = f.getModifiers();
                if (Modifier.isStatic(m) || Modifier.isFinal(m)) {
                    continue;
                }

                final Resource annot = f.getAnnotation(Resource.class);
                if (annot != null) {
                    if (!f.isAccessible()) {
                        f.setAccessible(true);
                    }

                    if (log.isTraceEnabled()) {
                        log.trace("doInjectDependencies(): Setting field " + f.getName() + " with bean '"
                                + annot.name() + "'");
                    }
                    f.set(obj, getBean(annot.name()));
                }
            }

            // inject methods
            for (Method method : currentClasz.getDeclaredMethods()) {

                final int m = method.getModifiers();
                if (Modifier.isStatic(m) || Modifier.isAbstract(m)) {
                    continue;
                }

                if (method.getParameterTypes().length != 1) {
                    continue;
                }

                if (!method.getName().startsWith("set")) {
                    continue;
                }

                final Resource annot = method.getAnnotation(Resource.class);
                if (annot != null) {
                    if (!method.isAccessible()) {
                        method.setAccessible(true);
                    }

                    if (log.isTraceEnabled()) {
                        log.trace("doInjectDependencies(): Invoking setter method " + method.getName()
                                + " with bean '" + annot.name() + "'");
                    }

                    method.invoke(obj, getBean(annot.name()));
                }
            }

            currentClasz = currentClasz.getSuperclass();

        } while (currentClasz != null);
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        this.factory = beanFactory;
    }
}